Rachmaninoff Basin [shown in false-color at bottom] is a peak-ring impact crater named for Russian composer Sergei Rachmaninoff. The smooth plains that fill its floor were probably molten magma that spewed from below. The plains inside the peak ring contain a set of concentric troughs. A recent MESSENGER flyby revealed the bright feature to the north of Rachmaninoff to be a volcanic vent.
X
Spanning 715 kilometers, Rembrandt (named after the Dutch painter) is one of the largest impact basins on the planet, second only to Caloris. By examining the craters that formed on top of it, researchers estimated Rembrandt Basin is 3.9 billion years old. The crater's interior includes two types of terrain (hummocky and smooth plains). The origin of the spokelike pattern of troughs in the center of the basin has baffled scientists since the troughs' discovery.
X
This beautiful image of the double-ringed Vivaldi Crater (named after Italian composer Antonio Vivaldi) was taken with the sun very low in the sky; the crater was near the terminator line, where day becomes night. Shadows more than 20 kilometers long creep into the 210-kilometer basin. Its prominent and nearly continuous inner ring measures about half the diameter of the outer ring.
X
Named for the medieval French poet and composer Guillaume de Machaut, this crater can be seen with the sun's slanting rays pushing shadows deep into the crater floor. The sharp contrast reveals the details and intricate features of the many smaller craters in and around Machaut. The largest crater within Machaut appears to have been inundated by lava flows similar to those that have filled most of the floor of the larger feature. The slightly smaller crater, which formed after the lava flows, excavated material below the lava-formed surface.
X
Matisse Crater, named for French artist Henri Matisse, sits in the planet's southern hemisphere. The MESSENGER spacecraft captured this image of the 210-kilometer-wide crater in January 2008. It is shown here near the terminator of the planet, which is the line between the day and night sides.
X
Photographed by Mariner 10 in the 1970s, the Discovery Scarp runs almost 350 kilometers from end to end. It cuts through two craters, one 35 and the other 55 kilometers in diameter. Just south of the larger crater, the scarp has lifted the terrain by almost three kilometers. Scarps indicate that Mercury shrank somewhat early in its history, most likely due to the cooling of the planet's interior.
X
So prominent is Debussy, a rayed impact crater, that it was first identified in 1969 from Earth-based radar observations. The bright rays extend hundreds of kilometers across the planet's southern hemisphere. Named for French composer Claude Debussy, the crater is 85 kilometers wide and is believed be geologically young. It is the second-largest rayed impact crater on Mercury, after Hokusai.
X
Derain Crater [at right in the image] has uncommonly dark material within and surrounding it, which may be of different composition than the bulk of Mercury's surface. The crater, named for French painter Andre Derain, is 180 kilometers wide and is so dark as to be easily viewed at great distances in space. Craters with similar dark material on or near their rims have been found on the floor of Caloris Basin.
X
Izquierdo Crater (named in honor of the 20th-century Mexican painter María Izquierdo) has a smooth floor, the result of volcanic lava that covered the surface. It is still possible to see outlines of the rims of so-called ghost craters (smaller, older impacts that were mostly buried by the lava flows that filled the basin) on Izquierdo's floor, where more recent impacts have resulted in some small, sharply defined craters.
X
Beagle Rupes, which runs through Sveinsdóttir Crater (named for Icelandic artist Júlíana Sveinsdóttir), is one of Mercury's highest and longest escarpments. The 600-kilometer feature was created by a thrust fault, which formed when the planet shrank as it cooled. Beagle Rupes crosscuts Sveinsdóttir and has uplifted the easternmost portion (right side) of the crater floor by almost a kilometer.
X
Pantheon Fossae, sometimes called the "spider," is a region in the center of the Caloris Basin containing numerous radial troughs whose origins are somewhat uncertain. The troughs are hundreds of kilometers in length and the central crater, named Apollodorus after the likely architect of the Pantheon temple in Rome, has a 40-kilometer diameter. Apollodorus Crater may have played a role in the formation of Pantheon Fossae, but it is also possible that the crater marks a later impactor that happened to strike near the center of the radial troughs.
X
The great Caloris impact basin, visible in this false-color image as a large, circular, yellowish-orange feature, is one of the largest impact basins in the solar system at about 1,550 kilometers in diameter. The color difference between Caloris and the surrounding plains indicates that the surface of the planet is not homogeneous. The bright spots near the basin's rim are believed to be remnants of Mercury's volcanic past.
X